CVE-2026-42639: GD Rating System SQLi Vulnerability

CVE-2026-42639 Overview

CVE-2026-42639 is an unauthenticated SQL injection vulnerability affecting the GD Rating System WordPress plugin in versions 3.6.2 and earlier. The flaw allows remote attackers to inject arbitrary SQL statements through plugin input parameters without authentication. Successful exploitation can expose database contents, enable data tampering on rating tables, and disrupt site availability. The vulnerability is tracked under CWE-89: Improper Neutralization of Special Elements used in an SQL Command.

Critical Impact
Unauthenticated attackers can issue arbitrary SQL queries against the WordPress database, exposing user data and rating records across affected sites.

Affected Products

GD Rating System WordPress plugin versions <= 3.6.2
WordPress sites with the vulnerable plugin installed and active
Multisite installations exposing the plugin endpoints

Discovery Timeline

2026-06-15 - CVE-2026-42639 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-42639

Vulnerability Analysis

The GD Rating System plugin fails to properly neutralize special characters in user-supplied input before incorporating that input into SQL statements. Because the affected endpoints do not require authentication, any unauthenticated remote actor can reach the injection point over the network. The attack requires no user interaction and has low complexity, making it suitable for automated scanning and mass exploitation against WordPress sites.

The injection occurs in plugin code paths that handle rating submissions or queries against the WordPress database. Crafted parameters are concatenated into SQL statements without parameterization or escaping, allowing attackers to alter query logic. The CWE-89 classification reflects the absence of prepared statements or proper input sanitization in the vulnerable code paths.

Root Cause

The root cause is the construction of SQL queries through direct string concatenation of attacker-controlled input. The plugin does not use $wpdb->prepare() with placeholders or apply equivalent sanitization functions before executing queries. This pattern violates standard WordPress secure coding guidance for database access.

Attack Vector

An attacker sends an HTTP request to a vulnerable plugin endpoint exposed by the WordPress site. The request includes payload data crafted to break out of the intended query context and append attacker-controlled SQL. Because no credentials are needed, exploitation can be performed by any internet-based actor with knowledge of the parameter names. Refer to the Patchstack advisory for CVE-2026-42639 for technical specifics.

Detection Methods for CVE-2026-42639

Indicators of Compromise

Web server access logs showing requests to GD Rating System endpoints containing SQL meta-characters such as ', --, UNION SELECT, or SLEEP(.
Unexpected entries, deletions, or modifications in the plugin's rating tables within the WordPress database.
New or unfamiliar administrator accounts and unexpected option changes in wp_options.
Outbound HTTP requests originating from the database host or PHP worker processes during request handling.

Detection Strategies

Inspect web server and WAF logs for SQL injection signatures targeting plugin parameters tied to gd-rating-system.
Enable MySQL or MariaDB general query logging temporarily to identify malformed or stacked queries originating from the plugin.
Compare current plugin file hashes against the official distribution to detect tampering following exploitation.

Monitoring Recommendations

Alert on HTTP requests to plugin URLs that include common SQLi payload tokens or encoded variants.
Monitor for spikes in 500-class responses and query execution time anomalies on the WordPress host.
Track creation of new database users, privilege changes, and reads against wp_users or wp_usermeta outside normal application flow.

How to Mitigate CVE-2026-42639

Immediate Actions Required

Update the GD Rating System plugin to a version newer than 3.6.2 as soon as a fixed release is available from the vendor.
Disable and remove the plugin on sites where the rating functionality is not required until a patch is applied.
Rotate WordPress administrator passwords and database credentials if exploitation is suspected.
Review wp_users, wp_usermeta, and option tables for unauthorized changes.

Patch Information

A fixed version should be obtained through the official WordPress plugin repository or the vendor's distribution channel. Consult the Patchstack advisory for CVE-2026-42639 for current patch status and recommended upgrade path.

Workarounds

Deploy a Web Application Firewall rule blocking SQL injection payloads against GD Rating System request paths.
Restrict access to the plugin's endpoints by IP allowlist where feasible.
Apply database least-privilege so the WordPress database account cannot perform schema changes or read sensitive system tables.

bash

# Example WAF rule concept (ModSecurity) blocking SQLi tokens on plugin paths
SecRule REQUEST_URI "@contains gd-rating-system" \
  "chain,id:1042639,phase:2,deny,status:403,msg:'Potential SQLi against GD Rating System'"
  SecRule ARGS "@rx (?i)(union\s+select|sleep\(|benchmark\(|--\s|';)"